As global air traffic has continued to grow overthe past two decades, it has effectively led to a sharp increase in the emissions and corresponding global warming through the 'greenhouse gas effect'. Apart from CO2 and H2O, NOx is the next major aviation-emitted species which significantly contributes to climatechange through its atmospheric chemistry leading to the formation of O3,which in itself is another major greenhouse gas.
Since global air traffic is a major source of tropospheric NOx,this thesis analyzed the contribution of aviation to tropospheric mixing ratiosof NOx and O3. The analyses were performed on 2 majoraspects: (A) to identify and understand the seasonal & zonal patterns with respect to aviation's contribution to tropospheric mixing ratio of NOx andO3, and (B) to comprehend the differences between 2 methodologies(called “Perturbation” & “Tagging”) in estimating aviation's contributionto tropospheric mixing ratio of NOx and O3. Inaddition to NOx and O3, background availability ofradicals OH and HO2 was also analyzed, since OH and HO2 arevital to the NOx-O3 chemistry.
The global climate-chemistry model EMAC (European Centre forMedium-Range Weather Forecasts – Hamburg (ECHAM)/MESSy Atmospheric Chemistry) was used, whereby the simulations were performed in quasi-chemistry transport model (QCTM) mode. The analyses presented an interesting overview of aviation's contribution to tropospheric NOx and O3.
